A large number of people, including those suffering from conditions such as diabetes, use some form of infusion therapy, such as daily insulin infusions, to maintain close control of their glucose levels. Currently, there are two principal modes of daily insulin therapy. The first mode includes syringes and insulin pens. These devices are simple to use and are relatively low in cost, but they require a needle stick at each injection, typically three to four times per day. The second mode includes infusion pump therapy, which entails the purchase of an insulin pump that lasts for about three years. The initial cost of the pump can be significant, but from a user perspective, the overwhelming majority of patients who have used pumps prefer to remain with pumps for the rest of their lives. This is because infusion pumps, although more complex than syringes and pens, offer the advantages of continuous infusion of insulin, precision dosing and programmable delivery schedules. This results in closer blood glucose control and an improved feeling of wellness.
The use of an infusion pump requires the use of a disposable component, typically referred to as an infusion set or pump set, which conveys the insulin from a reservoir within the pump into the skin of the user. An infusion set typically consists of a pump connector, a length of tubing, and a hub or base from which an infusion needle or a flexible cannula extends. The hub or base has an adhesive which retains the base on the skin surface during use, which may be applied to the skin manually or with the aid of a manual or automatic insertion device. Often, a user is further required to carry and provide a separate inserter. Accordingly, this method of treatment can become cumbersome and wasteful when dealing with the large number of required components.
Many infusion sets use a soft, Teflon-based cannula (also referred to as a catheter) to infuse insulin under the skin surface. Such Teflon cannulas are associated with less discomfort than steel cannulas. However, soft cannulas are prone to kink, which can delay or interrupt the patient's insulin delivery and reduce therapy. Most soft cannula infusion sets are inserted using a steel introducer needle that is positioned inside the cannula lumen and which extends beyond the cannula to initiate penetration. The introducer needle is then removed after catheter insertion.
Some infusion sets also use a separate high-impact, spring-loaded inserter that propels the introducer needle and cannula into the tissue at a desired speed, and to a desired depth. This process results in numerous steps which can be required to insert the infusion set, since it often requires the user to carry a separate insertion device, and load a set into the insertion device each time. The separate insertion device or inserter is therefore an added cost to the user and the additional steps of properly loading a device or set in the separate insertion device can become cumbersome.
As noted, most insulin infusion sets deliver medicament to the subcutaneous layers of skin using either rigid metal needles or flexible plastic cannulas. However, most insulin infusion sets do not provide any features to isolate the inserted needle or cannula from shock or other external forces. Also, as noted above, most insulin sets require separate inserters, which require the user to carry extra components for treatment. In regard to such separate inserters, an additional problem encountered by users of such separate inserters is the need to carry additional accessories and the difficulty of loading the infusion set onto the insertion device at each use.
Still further, in a conventional system, an introducer needle, catheter, and adhesive are all deployed at substantially the same time when inserted. During such “ballistic” insertion, there is a high-speed contact of the adhesive pad while the introducer needle and the catheter are being inserted, which may result in partially inserted catheters and/or incomplete adhesion.
Accordingly, a need exists for improved infusion sets that can deliver content to the subcutaneous skin layer while maintaining a degree of comfort to the user.